# Transistor amplifer problem

Discussion in 'Homework Help' started by lyj0211, Oct 27, 2013.

1. ### lyj0211 Thread Starter New Member

Oct 20, 2013
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Hi, I have a question in the attachment, and my workings are also attached. Just wish to know if my approach is correct? If not, what is my mistake? Thanks.

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2. ### The Electrician AAC Fanatic!

Oct 9, 2007
2,300
335
You appear to have correctly obtained YT. Now they want the voltage gain with Rs and RL included.

I don't know what they mean by y'ij S; can you explain what that is? I assume that y'ij means one of the 4 elements of YT, but I'm not sure why the "prime" is there. What's the difference between y21 and y'21?

3. ### WBahn Moderator

Mar 31, 2012
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4,917
I think it is poor grammar.

Lots of people (and I used to be one of them) like to use an apostrophe when they add letters to an abbreviation in order to not make it appear that the added letters are just part of the abbreviation itself. So if you have more than one A, they would say something like, "Then total up all the A's" instead of "Then total up all the As".

So I think that what we have here is someone saying to put it in terms of the collection of yij values and writing (yij)'s but the apostrophe is appearing above the ij subscript making it confusing.

At least I think this is what's happening -- and it explains what the 's' means, too.

4. ### The Electrician AAC Fanatic!

Oct 9, 2007
2,300
335
Another question I have for the OP is this:

You have determined that the y11 element of YT is

(s R1 C1 + 1)/R1 + (s Rf C2 + 1)/Rf

and the y12 element is

-(s Rf C2 + 1)/Rf

Suppose your result included the subexpression y11+y12. Do they want you to just write "y11+y12", or do they want

(s R1 C1 + 1)/R1 + (s Rf C2 + 1)/Rf - (s Rf C2 + 1)/Rf ?

5. ### The Electrician AAC Fanatic!

Oct 9, 2007
2,300
335
To me, "Then total up all the A's" seems to more clearly indicate at first glance that the single letter "A" is being converted to a plural than does "Then total up all the As", much as I hate to admit it!

See:

http://walkinthewords.blogspot.com/2009/05/grocers-apostrophe.html

And for some more discussion of other errors I am beginning to see more often:

http://www.theguardian.com/uk/2004/jul/08/books.booksnews